Agilent Technologies U2781A - Manual (Page 35)

Features and Functions 2
U2781A User’s Guide 23
System Reference Clock
The 10 MHz reference clock can come from two sources;
internal backplane oscillator and external clock source.
The internal oscillator on the USB backplane supplies an
independent 10 MHz system reference clock to each of the
USB slot. This 10 MHz reference clock is driven through an
independent buffer. Refer to
Figure 2- 3 for the block
diagram. Every clock trace is in equal distance to ensure
that the distance of the slot to the slot skew is minimized.
Users can use this common reference clock signal to
synchronize multiple modules in a measurement or control
system.
The default SCPI command of ACQuire:RSIGnal AUTO will
scan through and detect if there is any valid clock source
from the external BNC connector. If none is found, then the
internal 10 MHz clock source will be used.
The SCPI command below will direct the reference clock
source to the internal 10 MHz:
ACQuire:RSIGnal INT
U2781A UG.book Page 23 Friday, November 25, 2011 10:51 AM